Lecture 4 Flashcards
(7 cards)
1
Q
What are the main types of infectious agents?
A
- viruses
- bacteria
- fungi
- protozoa
- helminth parasites
2
Q
Eukaryotes vs prokaryotes
A
eukaryotes:
- well defined cytoskeleton
- membrane bound organelles
- well organised
- larger
- diploid/haploid
prokaryotes:
- cell wall of peptidoglycan
- no membrane bound organelles
- circular chromosome
- haploid
- less well defined cytoskeleton
- smaller
- simpler
3
Q
Viruses - features and examples
A
- infectious obligate intracellular parasites
- have RNA/DNA
- divide by budding out of host cells
- various routes of infection
E.G. HIV, SARS, Influenza, Polio
4
Q
Bacteria
A
- Replicate by binary fission
- Prokaryotes
- Have chromosomes - nuclear area where DNA is contained is the nucleoid
- Various routes of infection
- E.G. shigella causes shigellosis (faecal oral route and enters cell via vacuole and replicate intracellular)
Neisseria Meningitidis can cause septicaemia
5
Q
Fungi
A
- eukaryotes
- occur as yeasts (single cell), filaments of both
- yeast bud to divide
- have filaments called hyphae which have cross walls/septa (between cells in hyphae)
- E.G. Candida albicans causes Candida
6
Q
Protozoa
A
- These are unicellular eukaryotic organisms
- They are parasites that can infect the intestines, the blood and other tissues
- They replicate in the host via binary fission or by formation of trophozoites inside a cell
- They have a complicated life cycle involving two hosts
- Infection is acquired by ingestion or through a vector, such as an insect
- Two examples are malaria (Plasmodium) and leishmaniasis (Leishmania)
7
Q
Helminth parasites
A
- These include roundworms, tapeworms and flatworms
- They are multicellular eukaryotic organisms
- They are visible to the naked eye and can exist outside the host
- Can have simple or complex life cycles involving different hosts
- Examples include Ascaris (round worm called Ascaris lumbricoides) and schistosomiasis (flatworm called schistosome)
